* [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command
@ 2015-09-30 4:43 Kevin Buettner
2015-09-30 10:27 ` Pedro Alves
0 siblings, 1 reply; 5+ messages in thread
From: Kevin Buettner @ 2015-09-30 4:43 UTC (permalink / raw)
To: gdb-patches
Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
NULL return value after executing a finish command. See get_return_value()
in infcmd.c.
This patch avoids an eventual SIGSEV (caused by attempting to
derefrence a NULL pointer) by adding a suitable test to
finish_command_fsm_should_stop().
I encountered this problem while testing msp430:
(gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
finish
Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
ERROR: Process no longer exists
gdb/ChangeLog:
* infcmd.c (finish_command_fsm_should_stop): Don't attempt to
record a NULL value.
---
gdb/infcmd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index c4d7d8b..6be95e4 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
internal_error (__FILE__, __LINE__,
_("finish_command: function has no target type"));
- if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
+ if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID)
{
struct value *func;
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command
2015-09-30 4:43 [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command Kevin Buettner
@ 2015-09-30 10:27 ` Pedro Alves
2015-09-30 12:17 ` Kevin Buettner
0 siblings, 1 reply; 5+ messages in thread
From: Pedro Alves @ 2015-09-30 10:27 UTC (permalink / raw)
To: Kevin Buettner, gdb-patches
On 09/30/2015 05:43 AM, Kevin Buettner wrote:
> Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
> NULL return value after executing a finish command. See get_return_value()
> in infcmd.c.
>
> This patch avoids an eventual SIGSEV (caused by attempting to
> derefrence a NULL pointer) by adding a suitable test to
> finish_command_fsm_should_stop().
>
> I encountered this problem while testing msp430:
>
> (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
> finish
> Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
> ERROR: Process no longer exists
>
> gdb/ChangeLog:
> * infcmd.c (finish_command_fsm_should_stop): Don't attempt to
> record a NULL value.
> ---
> gdb/infcmd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gdb/infcmd.c b/gdb/infcmd.c
> index c4d7d8b..6be95e4 100644
> --- a/gdb/infcmd.c
> +++ b/gdb/infcmd.c
> @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
> internal_error (__FILE__, __LINE__,
> _("finish_command: function has no target type"));
>
> - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
> + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID)
> {
> struct value *func;
It's this else block that below sets rv->value in the first place:
if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
{
struct value *func;
func = read_var_value (f->function, NULL, get_current_frame ());
rv->value = get_return_value (func, rv->type);
rv->value_history_index = record_latest_value (rv->value);
}
So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION
targets?
I assume that it's record_latest_value that crashes? Isn't the right
fix instead:
rv->value = get_return_value (func, rv->type);
- rv->value_history_index = record_latest_value (rv->value);
+ if (rv->value != NULL)
+ rv->value_history_index = record_latest_value (rv->value);
?
Thanks,
Pedro Alves
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command
2015-09-30 10:27 ` Pedro Alves
@ 2015-09-30 12:17 ` Kevin Buettner
2015-09-30 12:21 ` Pedro Alves
0 siblings, 1 reply; 5+ messages in thread
From: Kevin Buettner @ 2015-09-30 12:17 UTC (permalink / raw)
To: Pedro Alves; +Cc: gdb-patches
On Wed, 30 Sep 2015 11:27:25 +0100
Pedro Alves <palves@redhat.com> wrote:
> On 09/30/2015 05:43 AM, Kevin Buettner wrote:
> > Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
> > NULL return value after executing a finish command. See get_return_value()
> > in infcmd.c.
> >
> > This patch avoids an eventual SIGSEV (caused by attempting to
> > derefrence a NULL pointer) by adding a suitable test to
> > finish_command_fsm_should_stop().
> >
> > I encountered this problem while testing msp430:
> >
> > (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
> > finish
> > Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
> > ERROR: Process no longer exists
> >
> > gdb/ChangeLog:
> > * infcmd.c (finish_command_fsm_should_stop): Don't attempt to
> > record a NULL value.
> > ---
> > gdb/infcmd.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/gdb/infcmd.c b/gdb/infcmd.c
> > index c4d7d8b..6be95e4 100644
> > --- a/gdb/infcmd.c
> > +++ b/gdb/infcmd.c
> > @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
> > internal_error (__FILE__, __LINE__,
> > _("finish_command: function has no target type"));
> >
> > - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
> > + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID)
> > {
> > struct value *func;
>
> It's this else block that below sets rv->value in the first place:
>
> if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
> {
> struct value *func;
>
> func = read_var_value (f->function, NULL, get_current_frame ());
> rv->value = get_return_value (func, rv->type);
> rv->value_history_index = record_latest_value (rv->value);
> }
>
> So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION
> targets?
>
> I assume that it's record_latest_value that crashes? Isn't the right
> fix instead:
>
> rv->value = get_return_value (func, rv->type);
> - rv->value_history_index = record_latest_value (rv->value);
> + if (rv->value != NULL)
> + rv->value_history_index = record_latest_value (rv->value);
>
You're right. (I honestly don't know what I was thinking.)
Please commit your patch instead.
Thanks,
Kevin
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command
2015-09-30 12:17 ` Kevin Buettner
@ 2015-09-30 12:21 ` Pedro Alves
2015-09-30 13:02 ` Kevin Buettner
0 siblings, 1 reply; 5+ messages in thread
From: Pedro Alves @ 2015-09-30 12:21 UTC (permalink / raw)
To: Kevin Buettner; +Cc: gdb-patches
On 09/30/2015 01:17 PM, Kevin Buettner wrote:
> On Wed, 30 Sep 2015 11:27:25 +0100
> Pedro Alves <palves@redhat.com> wrote:
>
>> On 09/30/2015 05:43 AM, Kevin Buettner wrote:
>>> Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
>>> NULL return value after executing a finish command. See get_return_value()
>>> in infcmd.c.
>>>
>>> This patch avoids an eventual SIGSEV (caused by attempting to
>>> derefrence a NULL pointer) by adding a suitable test to
>>> finish_command_fsm_should_stop().
>>>
>>> I encountered this problem while testing msp430:
>>>
>>> (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
>>> finish
>>> Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
>>> ERROR: Process no longer exists
>>>
>>> gdb/ChangeLog:
>>> * infcmd.c (finish_command_fsm_should_stop): Don't attempt to
>>> record a NULL value.
>>> ---
>>> gdb/infcmd.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/gdb/infcmd.c b/gdb/infcmd.c
>>> index c4d7d8b..6be95e4 100644
>>> --- a/gdb/infcmd.c
>>> +++ b/gdb/infcmd.c
>>> @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
>>> internal_error (__FILE__, __LINE__,
>>> _("finish_command: function has no target type"));
>>>
>>> - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
>>> + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID)
>>> {
>>> struct value *func;
>>
>> It's this else block that below sets rv->value in the first place:
>>
>> if (TYPE_CODE (rv->type) != TYPE_CODE_VOID)
>> {
>> struct value *func;
>>
>> func = read_var_value (f->function, NULL, get_current_frame ());
>> rv->value = get_return_value (func, rv->type);
>> rv->value_history_index = record_latest_value (rv->value);
>> }
>>
>> So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION
>> targets?
>>
>> I assume that it's record_latest_value that crashes? Isn't the right
>> fix instead:
>>
>> rv->value = get_return_value (func, rv->type);
>> - rv->value_history_index = record_latest_value (rv->value);
>> + if (rv->value != NULL)
>> + rv->value_history_index = record_latest_value (rv->value);
>>
>
> You're right. (I honestly don't know what I was thinking.)
>
> Please commit your patch instead.
I don't have a patch -- I wrote that hunk by hand
in the mail client. :-) Please fix up yours and push it.
Thanks,
Pedro Alves
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command
2015-09-30 12:21 ` Pedro Alves
@ 2015-09-30 13:02 ` Kevin Buettner
0 siblings, 0 replies; 5+ messages in thread
From: Kevin Buettner @ 2015-09-30 13:02 UTC (permalink / raw)
To: gdb-patches
On Wed, 30 Sep 2015 13:21:34 +0100
Pedro Alves <palves@redhat.com> wrote:
> >> I assume that it's record_latest_value that crashes? Isn't the right
> >> fix instead:
> >>
> >> rv->value = get_return_value (func, rv->type);
> >> - rv->value_history_index = record_latest_value (rv->value);
> >> + if (rv->value != NULL)
> >> + rv->value_history_index = record_latest_value (rv->value);
> >>
> >
> > You're right. (I honestly don't know what I was thinking.)
> >
> > Please commit your patch instead.
>
> I don't have a patch -- I wrote that hunk by hand
> in the mail client. :-) Please fix up yours and push it.
Oh, okay.
It's pushed.
Kevin
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-09-30 4:43 [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command Kevin Buettner
2015-09-30 10:27 ` Pedro Alves
2015-09-30 12:17 ` Kevin Buettner
2015-09-30 12:21 ` Pedro Alves
2015-09-30 13:02 ` Kevin Buettner
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